1. Field of the Invention
The present invention relates to IP-based packet-data cellular telecommunications, particularly to a method and system for more efficiently managing a mobile node dormant hand-off in a CDMA packet-data cellular telecommunications network.
2. Description of the Related Art
The CDMA 2000 cellular telecommunications network is a third generation (3G) IP-based cellular telecommunications network that uses the Code Division Multiple Access (CDMA) radio access technology for providing high-speed wireless service to mobile stations (MS). The services include interactive and background type of traffic classes, as well as conversational and streaming type of services, such as voice, text, internet and multimedia applications.
An exemplary IP-based CDMA 2000 cellular telecommunications network includes a plurality of mobile stations herein designated as Mobile Nodes (MNs) communicating over a radio interface with Base Transceiver Stations (BTS). Each group of one or more BTSs is connected to, and controlled by a Base Station Controller (BSC) having a Packet Control Function (PCF), which purpose is to manage the radio resources of each co-operating BTS. One or more Mobile Switching Centers (MSCs) may be connected to the IP-based CDMA 2000 cellular packet data telecommunications network for the provision of cellular service to subscribers, while a Packet Data Service Node (PDSN) performs the switching and routing functions directed to the packet data communications within the CDMA 2000 cellular telecommunications network.
The CDMA 2000 packet-data cellular telecommunications network provides Mobile IP service to packet mobile users. Mobile IP service is provided over a Point-to-Point Protocol (PPP) connection between the MN and the PDSN. When a PPP connection is established, negotiation messages are exchanged between the MN and the PDSN with regards to authentication and compression, followed by the MN's mobile IP registration. Thereafter, data may be sent from and to the MN, such as for example during a voice conversation or a file download. However, the MN becomes dormant when no data is transmitted for a certain period of time over the PPP connection. In instances when the MN is dormant, there is no traffic channel assigned to the mobile, although the PPP connection is maintained in both the MN and the PDSN.
When a mobile node moves within the packet data service area, instances arise when the MN is moved, or handed-off, from a first serving packet zone to a second service packet zone. This scenario involves the establishment of a new traffic channel between the new serving Base Station Controller (BSC) and the MN, as well as the establishment of a new PPP connection between the new serving PDSN and the MN.
Reference is now made to FIG. 1, wherein there is shown a nodal operation and signal flow diagram illustrating the complex and complicated prior art method for performing a dormant hand-off for a mobile node. Shown in FIG. 1 is a CDMA 2000 packet data cellular telecommunications network 100 comprising at least one Mobile Node (MN) 110, communicating over an air (radio) interface 112, and via a plurality of Base Transceiver Stations (BTSs, not shown) with a plurality of Base Station Controllers (BSCs), such as for example BSCs 114 and 116. The BSCs 14 and 116 may each comprise a Packet Control Function (PCF), which purpose is to manage the radio resources of each served BTS. Thus, the combined functionality of a BSC and a PCF is herein designated as BSC/PCF, although in some implementations the BSC and PCF may not be collocated. The network 100 may further comprise at least one Mobile Switching Center (MSC) 118 and a plurality of Packet Data Service Nodes (PDSNs), such as for example PDSN 120 and PDSN 122. The BSC/PCFs and the PDSNs may be connected with each other through an IP-based network 111. For the purpose of better understanding the present invention, it is assumed that a dormant MN 110 moves from a first packet zone, wherein it was served by BSC/PCF Source (BSC/PCF-S) 114 and PDSN Source (PDSN-S) 120, to a second packet zone wherein it is to be served by BSC/PCF Target (BSS/PCF-T) 116 and PDSN Target (PDSN-T) 122. By dormant MN, it is meant an MN that previously established a Point-to-Point Protocol (PPP) connection with a PDSN, such as for example with the PDSN-S 120, but that did not exchange data over that connection for a given period of time, thus causing the traffic channel between itself and the PDSN 120 to be dropped, while the PPP connection was kept active in both the MN and the PDSN-S.
Therefore, when the MN 110 crosses the packet zone boundary at dormant state, the MN 110 sends an origination request message 124 to the target BSC 116 via a BTS (not shown), for requesting service from BSC/PCF-T 116. Responsive to the receipt of the origination request message 124, the BSC/PCF-T 116 replies back to the MN 110 through a BS acknowledgement order message 129, for confirming that it accepts to serve the MN 110. The BSC 116 further exchanges with the serving MSC 118 serving set up messages 128 and 130, through which the MSC 118 is requested, and accepts, to support cellular service for the MN 110. Since the MN 110 has moved to a new packet zone, the target BSC 116 selects a new PDSN, such as the target PDSN 122 for providing mobile IP service for the MN 110, and thus sends an A11 registration request message 132 to the target PDSN 122 for requesting the set up of an A10 connection (also called herein a Radio network Packet data serving node session or connection, (RP) with the MN 110. Responsive to the receipt of the A11 registration request message 132, the target PDSN 122 replies back to the BSC/PCF-T 116 with an A11 registration reply message 136. The BSC/PCF-T 116 then sends to the MSC 118 an Assignment Failure message 137 informing the MSC that the MN 110 is dormant. At this stage, the PDSN-T 122 may begin to send data packets for the MN 110, action 139. In the prior art technique, the BSC/PCF-T 116 further signals the MSC 118 with a BS Service Request 141 for requesting packet data service, to which the MSC 118 responds with a BS service response 143 accepting the provision of packet data service. The MSC 118 further sends a Paging Request 145 to the BSC/PCF-T 116 to establish a, mobile terminated packet data call. Responsive to 145, the BSC/PCF-T 116 further issues a Page Message 149 over the paging channel, and receives back from the MN 110 a Page Response Message 151 over the access channel. Upon receipt of message 151, the BSC/PCF-T 116 places the Page Reponses Message in a Complete L3 Info Message 153 and sends it to the MSC 118. The BSC/PCF-T 116 also acknowledges to the MN 110 the receipt of the Page Response Message 151, in message 155. Responsive to the receipt of the message 153, the MSC finally requests the establishment of a traffic channel with the MN 110, action 157. With reference being now made jointly to FIG. 1.a and FIG. 1.b, channel establishment procedures take place in 159 resulting in a traffic channel 161 to be established between the MN 110 and the BSC/PCF-T 116. The data packets received from the PDSN-T 122 in 139, and that were buffered by the BSC/PCF-T 116, may now be sent to the MN 110, action 163, for the establishment of the new PPP connection 150 through PPP connection establishment procedure 148.
As it may be seeing, the prior art method for performing a dormant hand-off in a CDMA 2000 packet-data cellular telecommunications network is complicated and comprises unnecessary signalling that overuses the network's communications resources. For example, having a paging procedure involving at least messages 145, 149, 151, and 153 in order to locate yet again an MN that just registered with the BSC/PCF-T 116 is unnecessary.
It would be advantageous to have simpler method for performing a dormant hand-off in the CDMA 200 packet-data cellular telecommunications network, that takes advantage of the information already passed among the network's nodes for avoiding signalling associated with the transmission of redundant and unnecessary information.
The present invention provides such a solution.